Selected transition metal complexes of iminocarboxylate and iminoamido ligands, sometimes in the presence of certain cocatalysts, are catalysts for the (co)polymerization of olefins such as ethylene, xcex1-olefins, and certain polar olefins such as olefinic esters. Preferred transition metals include nickel, titanium and zirconium. Also described are certain xe2x80x9cZwitterionicxe2x80x9d transition metal complexes as polymerization catalysts for making polar copolymers.
Olefins may be polymerized by a variety of transition metal containing catalysts, for example metallocene and Ziegler-Natta type catalysts. More recently, late transition metal containing polymerization catalysts have also been discovered, and among them are nickel and other transition metal containing catalysts in which the metal atom is complexed to a monoanionic and presumed bidentate ligand, see for instance WO9842664, WO9842665, U.S. Pat. Nos. 6,060,569, 6,174,975 and S. D. Ittel, et al., Chem. Rev., vol. 100, p. 1169-1203 (2000) (and references cited therein). S. Y. Desjardins, et al., J. Organometal. Chem., vol. 515, p. 233-243 (1996), ibid., vol. 544, p. 163-174 (1997), describe the oligomerization/polymerization of ethylene using nickel complexes of certain pyridine carboxylates.
U.S. Pat. No. 6,174,976 describes the use of certain neutral nickel complexes of ligands containing imino and carboxylate groups to polymerize hydrocarbon monoolefins.
In the following references, Zwitterionic nickel catalysts based on phosphine carboxylate ligands were utilized to carry out ethylene oligomerizations; however, polar monomers were not incorporated in any of the oligomers made with these systems: Komon, Z. J. A., et. al., J. Am. Chem. Soc., 122, 1830-1831 (2000); Komon, Z. J. A., et. al., J. Am. Chem. Soc., 122, 12379-12380 (2000).
Zwitterionic systems have been proposed in U.S. Pat. Nos. 6,103,658 and 6,200,925, but no polar monomers were incorporated in any of the polymers made with these systems.
All of the above publications are incorporated by reference herein for all purposes as if fully set forth.
None of these publications describes the complexes disclosed herein. Since polyolefins are important commercial materials, new catalysts for their manufacture are constantly being sought.
This invention concerns a process for the polymerization of olefins, comprising the step of contacting, under olefin polymerizing conditions, a monomer component comprising one or more of an olefin of the formula H2C=CHR4, a norbornene, a styrene, a cyclopentene or a polar olefin, especially an olefin of the formula H2C=CHR4 or a polar olefin of the formula H2C=CHR5CO2R6, with a transition metal complex of a ligand of the formula 
wherein:
Y is oxo, NR12 or PR12 
z is O, NR13, S or PR13;
each of R1, R2 and R3 is independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group;
n is 0 or 1;
R4 is hydrogen, alkyl or substituted alkyl;
R5 is a covalent bond, alkylene or substituted alkylene;
R6 is hydrogen, a metal cation, hydrocarbyl or substituted hydrocarbyl;
each R12 is independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group;
each R13 is independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group;
and provided that any two of R1, R2 and R3 geminal or vicinal to one another taken together may form a ring.
In the above mentioned process, the transition metal complex of (I) may in and of itself be an active catalyst, or may be xe2x80x9cactivatedxe2x80x9d by contact with a cocatalyst/activator as further described below.
The present invention also concerns the ligand of the formula (I), transition metal complexes thereof, and polymerization catalyst components comprising these transition metal complexes.
This invention also concerns a process for the manufacture of a polar copolymer, wherein one or more hydrocarbon olefins, one or more polar olefins, and a polymerization catalyst system having a transition metal complex component containing a transition metal of groups 6-11 or a lanthanide metal, are contacted under polymerizing conditions to form said polar copolymer, wherein the transition metal complex component comprises a Zwitterionic complex.
These and other features and advantages of the present invention will be more readily understood by those of ordinary skill in the art from a reading of the following detailed description. It is to be appreciated that certain features of the invention which are, for clarity, described below in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination.
Herein, certain terms are used. Some of them are:
A xe2x80x9chydrocarbyl groupxe2x80x9d is a univalent group containing only carbon and hydrogen. As examples of hydrocarbyls may be mentioned unsubstituted alkyls, cycloalkyls and aryls. If not otherwise stated, it is preferred that hydrocarbyl groups (and alkyl groups) herein contain 1 to about 30 carbon atoms.
By xe2x80x9csubstituted hydrocarbylxe2x80x9d herein is meant a hydrocarbyl group that contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected (e.g., an inert functional group, see below). The substituent groups also do not substantially detrimentally interfere with the polymerization process or operation of the polymerization catalyst system. If not otherwise stated, it is preferred that substituted hydrocarbyl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of xe2x80x9csubstitutedxe2x80x9d are chains or rings containing one or more heteroatoms, such as nitrogen, oxygen and/or sulfur, and the free valence of the substituted hydrocarbyl may be to the heteroatom. In a substituted hydrocarbyl, all of the hydrogens may be substituted, as in trifluoromethyl.
By xe2x80x9c(inert) functional groupxe2x80x9d herein is meant a group, other than hydrocarbyl or substituted hydrocarbyl, which is inert under the process conditions to which the compound containing the group is subjected. The functional groups also do not substantially deleteriously interfere with any process described herein that the compound in which they are present may take part in. Examples of functional groups include, for example, halo (fluoro, chloro, bromo and iodo), ether such as xe2x80x94OR22 wherein R22 is hydrocarbyl or substituted hydrocarbyl, silyl, substituted silyl, thioether and tertiary amino. In cases in which the functional group may be near a transition metal atom, the functional group alone should not coordinate to the metal atom more strongly than the groups in those compounds that are shown as coordinating to the metal atom, that is they should not displace the desired coordinating group.
By a xe2x80x9ccocatalystxe2x80x9d or a xe2x80x9ccatalyst activatorxe2x80x9d is meant one or more compounds that react with a transition metal compound to form an activated catalyst species. One such catalyst activator is an xe2x80x9calkyl aluminum compoundxe2x80x9d which, herein, is meant a compound in which at least one alkyl group is bound to an aluminum atom. Other groups such as, for example, alkoxide, hydride and halogen may also be bound to aluminum atoms in the compound.
By xe2x80x9cneutral Lewis basexe2x80x9d is meant a compound, that is not an ion, which can act as a Lewis base. Examples of such compounds include ethers, amines, thioethers, olefins and organic nitrites.
By xe2x80x9cneutral Lewis acidxe2x80x9d is meant a compound, that is not an ion, which can act as a Lewis acid. Examples of such compounds include boranes, alkylaluminum compounds, aluminum halides and antimony [V] halides.
By xe2x80x9ccationic Lewis acidxe2x80x9d is meant a cation which can act as a Lewis acid. Examples of such cations are sodium and silver cations.
By an xe2x80x9cempty coordination sitexe2x80x9d is meant a potential coordination site on a transition metal atom that does not have a ligand bound to it. Thus if an olefin molecule (such as ethylene) is in the proximity of the empty coordination site, the olefin molecule may coordinate to the metal atom.
By a xe2x80x9cligand into which an olefin molecule may insert between the ligand and a metal atomxe2x80x9d, or a xe2x80x9cligand that may add to an olefinxe2x80x9d, is meant a ligand coordinated to a metal atom which forms a bond (L-M) into which an olefin molecule (or a coordinated olefin molecule) may insert to start or continue a polymerization. For instance, with ethylene this may take the form of the reaction (wherein L is a ligand): 
By a xe2x80x9cligand which may be displaced by an olefinxe2x80x9d is meant a ligand coordinated to a transition metal which, when exposed to the olefin (such as ethylene), is displaced as the ligand by the olefin.
By a xe2x80x9cmonoanionic ligandxe2x80x9d is meant a ligand with one negative charge.
By a xe2x80x9cneutral ligandxe2x80x9d is meant a ligand that is not charged.
xe2x80x9cAlkyl groupxe2x80x9d and xe2x80x9csubstituted alkyl groupxe2x80x9d have their usual meaning (see above for substituted under substituted hydrocarbyl). Unless otherwise stated, alkyl groups and substituted alkyl groups preferably have 1 to about 30 carbon atoms.
By xe2x80x9carylxe2x80x9d is meant a monovalent aromatic group in which the free valence is to the carbon atom of an aromatic ring. An aryl may have one or more aromatic rings which may be fused, connected by single bonds or other groups.
By xe2x80x9csubstituted arylxe2x80x9d is meant a monovalent aromatic group substituted as set forth in the above definition of xe2x80x9csubstituted hydrocarbylxe2x80x9d. Similar to an aryl, a substituted aryl may have one or more aromatic rings which may be fused, connected by single bonds or other groups; however, when the substituted aryl has a heteroaromatic ring, the free valence in the substituted aryl group can be to a heteroatom (such as nitrogen) of the heteroaromatic ring instead of a carbon.
By a xe2x80x9cxcfx80-allyl groupxe2x80x9d is meant a monoanionic ligand comprised of 1 sp3 and two sp2 carbon atoms bound to a metal center in a delocalized xcex73 fashion indicated by 
The three carbon atoms may be substituted with other hydrocarbyl groups or functional groups.
By a xe2x80x9cstyrenexe2x80x9d herein is meant a compound of the formula 
wherein R43, R44, R45, R46 and R47 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group, all of which are inert in the polymerization process. It is preferred that all of R43, R44, R45, R46 and R47 are hydrogen. Styrene (itself) is a preferred styrene.
By a xe2x80x9cnorbornenexe2x80x9d is meant ethylidene norbornene, dicyclopentadiene or a compound of the formula 
wherein R40 is hydrogen or hydrocarbyl containing 1 to 20 carbon atoms. It is preferred that R40 is hydrogen or alkyl, more preferably hydrogen or n-alkyl, and especially preferably hydrogen. The norbornene may be substituted by one or more hydrocarbyl, substituted hydrocarbyl or functional groups in the R40 or other positions, with the exception of the vinylic hydrogens, which remain. Norbornene (itself) is a preferred norbornene.
By a xe2x80x9ccyclopentenexe2x80x9d herein is meant cyclopentene or a substituted cyclopentene. Preferred cyclopentenes are cyclopentene, 1- or 3-methylcyclopentene and 1- or 3-ethylcyclo-pentene, and cyclopentylcyclopentene, and cyclopentene is more preferred.
By xe2x80x9cEsxe2x80x9d is meant a parameter to quantify steric effects of various groupings, see R. W. Taft, Jr., J. Am. Chem. Soc., vol. 74, p. 3120-3128 (1952), and M. S. Newman, Steric Effects in Organic Chemistry, John Wiley and Sons, New York, 1956, p. 598-603, which are both hereby included by reference. For the purposes herein, the Es values are those described for o-substituted benzoates in these publications. If the value of Es for a particular group is not known, it can be determined by methods described in these references.
By xe2x80x9caryl substituted in at least one position vicinal to the free bond of the aryl group,xe2x80x9d is meant the bond to one of the carbon atoms next to the free valence of the aryl group is something other than hydrogen. For example for a phenyl group, it would mean the 2 position of the phenyl group would have something other than hydrogen attached to it. A 1-naphthyl group already has something other than hydrogen attached to one of the vicinal carbon atoms at the fused ring junction, while a 2-napthyl group would have to be substituted in either the 1 or 3 positions to meet this limitation. A preferred aryl substituted in at least one position vicinal to the free bond of the aryl group is a phenyl group substituted in the 2 and 6 positions, and optionally in the other positions.
By a xe2x80x9cpolar (co)monomerxe2x80x9d or xe2x80x9cpolar olefinxe2x80x9d is meant an olefin which contains elements other than carbon and hydrogen. When copolymerized into a polymer the polymer is termed a xe2x80x9cpolar copolymerxe2x80x9d. Useful polar comonomers are found in U.S. Pat. No. 5,866,663, WO9905189, WO9909078 and WO9837110, and S. D. Ittel, et al., Chem. Rev., vol. 100, p. 1169-1203(2000), all of which are incorporated by reference herein for all purposes as if fully set forth. Also included as a polar comonomer is CO (carbon monoxide).
By xe2x80x9cunder polymerization conditionsxe2x80x9d is meant the conditions for a polymerization that are usually used for the particular polymerization catalyst system being used. These conditions include paraneters such as pressure, temperature, catalyst and cocatalyst (if present) concentrations, the type of process such as batch, semibatch, continuous, gas phase, solution or liquid slurry etc., except as modified by conditions specified or suggested herein. Conditions normally done or used with the particular polymerization catalyst system, such as the use of hydrogen for polymer molecular weight control, are also considered xe2x80x9cunder polymerization conditionsxe2x80x9d. Other polymerization conditions such as presence of hydrogen for molecular weight control, other polymerization catalysts, etc., are applicable with this polymerization process and may be found in the references cited and incorporated herein.
The polymerizations herein are carried out by a transition metal complex of anion (I). In (I), and in all complexes and compounds containing (I) or its parent conjugate acid, it is preferred that:
Y is oxo or NR12;
Z is O or NR13;
n is 0; and/or
R1 is hydrocarbyl or hydrogen, more preferably hydrogen or alkyl; especially preferably alkyl, and particularly methyl; and/or
R2 and R3, when present (n is 1), are each independently hydrocarbyl or hydrogen, more preferably hydrogen or alkyl; especially preferably methyl or hydrogen; and/or
R12 and R13 are each independently hydrocarbyl or substituted hydrocarbyl, more preferably aryl, substituted aryl or alkyl; more preferably 9-phenanthryl, 1- or 2-naphthyl or substituted 1- or 2-naphthyl, or 
wherein each of R7, R8, R9, R10 and R11 is independently hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group. In another preferred form, one or both of R12 and/or R13 are aryl or substituted aryl in which at least one bond vicinal to the free bond of the aromatic group is substituted, or R12 and/or R13 are a group with an Es of less than about xe2x88x921.0, more preferably less than about xe2x88x921.5, or both.
In (I) and its complexes, more specific preferred combinations are:
when Y is O (oxo) and Z is NR13; R1 is hydrogen or hydrocarbyl, more preferably alkyl or aryl; R13 is hydrocarbyl or substituted hydrocarbyl having an Es of less than xe2x88x921.0, or aryl or substituted aryl in which at least one bond vicinal to the free bond of the aromatic group is substituted, more preferably 2,6-disubstituted phenyl (optionally with one or more of the other positions on the phenyl group substituted); or
when Y is NR12 and Z is NR13; R1 is hydrogen or hydrocarbyl, more preferably alkyl or aryl; one or both of R12 and R13 is hydrocarbyl or substituted hydrocarbyl having an Es of less than xe2x88x921.0, or aryl or substituted aryl in which at least one bond vicinal to the free bond of the aromatic group is substituted, more preferably R12 is 2,6-disubstituted phenyl (optionally with one or more of the other positions on the phenyl group substituted).
In (II) it is preferred that one or both of R7 and R11 are other than hydrogen, more preferably hydrocarbyl or a functional group, especially preferably alkyl containing 1 to 6 carbon atoms, aryl (such as pehnyl or a hydrocarbyl substituted phenyl such as 4-t-butylphenyl), halo or alkoxy.
A specific preferred ligand (I) (and its corresponding conjugate acid and transition metal complexes) include one in which R1 is methyl; n is 0; Y is NR12, R12 is (II); R8, R9 and R10 are hydrogen; and R7 and R11 are isopropyl.
In transition metal complexes of (I), useful transition metals include Group 3-11 (IUPAC) transition metals and lanthanide metals such as Ni, Pd, Pt, Fe, Co, Ti, Zr, V, Hf, Cr, Mn, Ru, Rh, Re, Os, Ir, Cu and the rare earths (lanthanides). Preferred transition metals are Ni, Zr, Ti, Fe, Co and Cu, and Ni, Ti and Zr are more preferred. When Ni, Fe or Co are the transition metals a preferred oxidation state is [II], when Zr or Ti are the transition metals a preferred oxidation state is [IV], and when Cu is the transition metal preferred oxidation states are [I] and [II].
The complexes of the transition metals may contain one or two of the ligands (I) per transition metal atom, depending on the particular transition metal. For example early transition metals which may be pentacoordinate or hexacoordinate may have one or two ligands per metal atom respectively, as exemplified in the structures 
wherein, for example, M (the transition metal) may be Ti [IV] or Zr[IV], and each L1 is a monodentate, monoanionic ligand such as chloride.
For some late transition metals such as Ni which tend to be tetracoordinate, a typical complex may be 
wherein, for example, M (the transition metal) is Ni[II], L1 is a monoanionic, monodentate ligand such as chloride or methyl, and L2 is a monodentate neutral ligand such as acetonitrile, or an empty coordination site, or L1 and L2 taken together are a monoanionic, bidentate ligand such as a xcfx80-allyl group.
Although the complexes of (I) are drawn with (I) as a bidentate ligand it is to be understood that this is for convenience only in representing these complexes, and any transition metal complex of (I), whether (I) is monodentate, bidentate, etc., is included within the meaning of a complex of (I).
It is believed that, in the active polymerization catalyst species herein, at least one of the ligands (e.g., L1) is preferably a ligand that may add to an olefin. It is further believed that, in the late transition metal active polymerization catalyst species herein, another of the ligands (e.g., L2) is a neutral ligand which may be displaced by an olefin, or an empty coordination site, or the olefin itself. Examples of ligands that may add to an olefin include hydrocarbyl and substituted hydrocarbyl (especially phenyl and alkyl, and particularly methyl), hydride and acyl. Examples of ligands which may be displaced by ethylene include phosphines (such as triphenylphosphine), nitrites (such as acetonitrile), ethers (such as ethyl ether), pyridine and tertiary alkylamines (such as TMEDA (N,N,Nxe2x80x2,Nxe2x80x2-tetramethylethyenediamine)).
Herein, as indicated above, ligands that may add to an olefin can be L1, and ligands which may be displaced by ethylene may be L2, as for instance shown in (V) and (VI). 
Particularly at the beginning of the polymerization, L1 and L2 taken together may be a bidentate monoanionic ligand into which an olefin molecule (such as ethylene) may insert between that ligand and the transition metal atom, such as xcfx80-allyl- or xcfx80-benzyl-type ligands such as 
wherein R is hydrocarbyl. In this instance, sometimes it may be necessary to add a neutral Lewis acid cocatalyst such as triphenylborane or tris(pentafluorophenyl)borane to initiate the polymerization, see below and for instance U.S. Pat. No. 5,880,241, which is incorporated by reference herein for all purposes as if fully set forth. For a summary of which ligands olefins may insert into (between the ligand and transition metal atom) see for instance J. P. Collman, et al., Principles and Applications of Organotransition Metal Chemistry, University Science Books, Mill Valley, Calif., 1987.
If for instance L1 is not a ligand into which ethylene may insert between it and the transition metal atom, it may be possible to add a cocatalyst that may convert L1 into a ligand which will undergo such an insertion. Thus if L1 is halo such as chloride or bromide, carboxylate or acetylacetonate, it may be converted to hydrocarbyl such as alkyl by use of a suitable alkylating agent such as an alkylaluminum compound, a Grignard reagent or an alkyllithium compound. It may be converted to hydride by used of a compound such as sodium borohydride.
It is preferred that the alkylating compound (cocatalyst or activator) be both an alkylating compound and a neutral Lewis acid. A preferred cocatalyst is an alkylaluminum compound, and useful alkylaluminum compounds include trialkylaluminum compounds such as triethylaluminum, trimethylaluminum and tri-i-butylaluminum, alkyl aluminum halides such as diethylaluminum chloride and ethylaluminum dichloride, and aluminoxanes such as methylaluminoxane. Alternatively, a combination of an alkylating agent (which may be a relatively weak Lewis acid) and another stronger neutral Lewis acid may be present as the cocatalyst(s). Even if L1 is already a ligand into which ethylene may insert, it may be advantageous to have a neutral Lewis acid present as a cocatalyst. It is preferred when a late transition metal, especially Ni, is used, that a neutral Lewis acid be present, especially at lower process temperatures.
Once the polymerization has started on a particular transition metal site, the ligand into which an olefin may insert will often be a ligand which is in fact the growing polymer chain whose composition will be the monomer(s) being polymerized and the end group the original L1 which the first olefin molecule inserted into (between the ligand and metal). This polymer ligand may be represented by the group xe2x88x92PL1, wherein P is a divalent xe2x80x9cpolymericxe2x80x9d (but which may have only one or few repeat units at times), and will be understood to contain one or more repeat units derived from the monomer(s) used. If chain transfer occurs, for instance by xcex2-hydride elimination to form a hydride ligand on the transition metal, the end group of the next polymer chain will be hydrogen.
A general formula for a transition metal complex useful herein can be written as (L1)x(L2)y(L3)zM (VIII) wherein L1 and L2 are as defined above, L3 is (I), z is 1 or 2, M is a transition metal of oxidation state q, y is an integer of 1 to 3, and x=(qxe2x88x92z). L1 and L2 may have the variations mentioned above, and when L1 and L2 are the indicated groups, the transition metal compound may inherently be an active polymerization catalyst. Table 1 gives preferred transition metal compounds (VIII). Preferred ligands L3 for these compounds are as described above.
Included within the meaning of the transition metal complexes of (I) herein are Lewis acid adducts of such complexes. By this is meant an adduct formed between the transition metal complex of (I) and a neutral Lewis acid. The structures of such adduct complexes may often be written as 
wherein R1, R2, R3, n, Z, Y, M, L1 and L2 are as defined above, and LA (by itself) is a neutral Lewis acid. Preferably the metal is a late transition metal of Groups 6-11, more preferably Groups 8-11. Suitable neutral Lewis acids include boranes such as tris(pentafluorophenyl)borane, triphenylborane, and aluminanes such as trihydrocarbylaluminum, especially trialkylaluminum (for example triethylaluminum), and others which can coordinate with the transition metal complex.
More generally (with other suitable ligands as well, see below) such complexes, called herein Zwitterionic complexes, are particularly useful in the copolymerization of a hydrocarbon olefin (such as ethylene) and a polar comonomer, especially vinyl polar comonomers (in a vinyl polar comonomer the polar group is attached directly to a vinylic carbon atom, as in acrylic monomers), particularly when using a complex of a late transition metal of Groups 8-11. Preferred metals are Pd and Ni, and Ni is especially preferred. Suitable neutral Lewis acids include tris(pentafluorophenyl)borane, triphenylborane, trihydrocarbylaluminum, especially trialkylaluminum (for example triethylaluminum), and others which can coordinate with the transition metal complex. Preferably the Lewis acid should not react with any other component of the polymerization catalyst system, for example not contain xe2x80x9cactivexe2x80x9d halogen groups which may react with an alkylaluminum compound, if an alkylaluminum compound is present in the polymerization process. The Lewis acid is coordinated to a Lewis base which is present in the ligand of the metal complex. Therefore, the Lewis acid may be removed from ligand (metal complex) by addition of a Lewis base which is a stronger Lewis base than the group on the ligand to which the Lewis acid is coordinated (bound). Lewis acid in this instance does not mean a Lewis acid which is relatively permanently covalently bound to the ligands, for example xe2x80x94B(aryl)2 where the boron is covalently bound to a carbon atom of the ligand.
When using Zwitterionic materials to form polar comonomers, preferred hydrocarbon olefins are ethylene and H2C=CHR4, wherein R4 is alkyl or substituted alkyl, preferably n-alkylene, and ethylene is especially preferred. A preferred polar olefin is H2C=CHR5CO2R6, particularly wherein R5 is a covalent bond, and R6 is hydrocarbyl or substituted hydrocarbyl.
When the transition metal complex in the Zwitterionic compound is a Ni complex, it is preferred that the Ni atom be coordinated to a neutral bidentate ligand or a monoanionic bidentate ligand. In order to form a Zwitterionic compound using a complex of any transition metal with any ligand, the ligand will normally contain a group which is a Lewis base. The combination of this Lewis base group and neutral Lewis acid chosen will normally have a large enough difference in Lewis acidity and basicity to form a complex. For example a group which is a weak Lewis base may form a Zwitterionic compound with a strong Lewis acid, and vice versa.
Generally speaking a Zwitterionic complex will be detectable using any number of methods. For instance it may be isolable as the Zwitterionic complex, and the structure proven by various methods such as X-ray diffraction or various spectroscopic methods such as NMR or infrared spectroscopy. Its presence may also be shown in solution, such as by ultraviolet, infrared or NMR spectroscopy. If any of these or other methods shows the presence of the Zwitterionic compound, it is deemed this complex is an active polymerization catalyst.
In any of the polymerization processes herein in which a polar comonomer is copolymerized, and in any formation of any polar copolymer, it is preferred that the molar ratio of the total of the polar comonomers present to any added Lewis acid is at least 2:1, preferably at least 10:1. Polar comonomers, such acrylic-type monomers, have been copolymerized in certain situations by destroying their Lewis basic (or coordinating) character by reacting them with a Lewis acid, to form a Lewis acid xe2x80x9csaltxe2x80x9d of the polar comonomer. While this may often help to form the polar copolymer, later removal of the stoichiometric amount (relative to the polar comonomer) of Lewis acid is difficult and expensive.
It is also noted that when Zwitterionic complexes are used as part of the olefin polymerization catalyst system, even in the polymerization of hydrocarbon olefins (no polar olefins present), such as ethylene, there is an improvement in the polymerization, such as improved polymer productivity and/or longer catalyst life.
In one preferred form of the present Zwitterionic compounds, the Lewis acid which complexes to the ligand in the transition metal complex preferably is not in a position to readily interact with any polar groups on the polar copolymer which is forming, particularly polar groups very close to the metal atom on the polymerizing polymer chain. This is particularly preferred with Ni complexes.
Dreiding Stereomodels (Manufactured by Bxc3xcchi Laboratory-Techniques, Ltd., Switzerland, and available in the USA from Aldrich Chemical Company or other sources. The Normal Set, Aldrich Catalog Number Z24,787-1 and the Porphyrin Set, Aldrich Catalog Number Z25,644-7, together provide the parts required for this purpose) are a useful tool to understand the geometries of various catalytic complexes. They provide very precise bond distances and angles while maintaining all of the flexibility normally associated with atom-atom bonds. They are available with the nickel, carbon, nitrogen, oxygen, phosphorus, sulfur and all other atoms necessary for building all of the ligands and complexes discussed in this case. They also come with a convenient ruler to measure distance between atom centers in xc3x85ngstroms. They are useful to determine the potential for interaction between the polar functionality on the growing polymer chain and any Lewis acidic site in the complex. Through rotation about the Nixe2x80x94C bond and any other Cxe2x80x94C bonds in the polymer chain bound to the nickel center, the polar functionality is able to sweep out a conical volume of space. If there is any available Lewis acidic site within that space (which may also rotate into that space), it is presumed that there can be a bonding interaction with that Lewis acidic site which would compete in an equilibrium with the nickel center for the lone pair electrons on the polar functionality. The potential for interaction may be determined through the following construct.
Starting with a square planar nickel atom, the complex is constructed by binding the ligand to two of the adjacent coordination sites on nickel. A carbon atom is placed at a third site on nickel. The fourth coordination site on nickel is occupied by X, and A represents a ligand or a vacant coordination site. 
A solid cone is defined by the angle, xcex8, and the distance (in xc3x85), xcex, in the manner shown, with the axis of the cone along the nickel-carbon bond. The maximum value possible for xcex8 is 180xc2x0. 
The conical volume of space through which the polar functionality attached to the growing polymer chain may sweep by means of rotation of the Nixe2x80x94C and Cxe2x80x94C bonds is determined through use of the models. This cone is the Lewis Acid Interaction Cone or LAIC. The angle increases for each additional carbon atom located between the nickel center and the polar functionality. For instance, in the case of methyl acrylate, xcex8 varies from 65 to 120xc2x0 in going from one to three carbon atoms between the nickel center and the carbonyl functionality.
These are taken herein as typical values of the LAIC for a variety of commercially important polar olefins. Any catalyst complex having a Lewis acidic atom whose atomic center is within the LAIC may bond to the electron pair available on the polar functionality through said Lewis acid. On the other hand, the Lewis acid in 
is well outside the LAIC even at xcex8=130xc2x0 (and is preferred herein) and will not be involved in binding to the Lewis-basic electron pair of the polar functionality. To be one type of preferred Lewis acid herein, the LAIC should be greater than 130xc2x0, preferably greater than about 150xc2x0.
The volume swept out by the rotating carbonyl is also limited in its distance, xcex, from the nickel center. It may not come closer to nickel than the bonding distance of just over 2 xc3x85. Maximizing the distance from the metal center, one observes 4.5, 5.0 and 6.5 xc3x85, respectively for one, two and three carbons between nickel and the carbonyl group. These distances impose a further constraint upon the position of the Lewis acid, but the distance from the metal center is seldom a limitation in the construction of ligands.
When Z in (I) is O, the ligand may be made by reaction of an amine R12NH2 with a metal salt, preferably an alkali metal salt, of an appropriate carboxylic acid 
wherein R1, R2, R3, R12 and n are as defined above. This reaction yields the ligand (I) as its (alkali) metal salt. This salt may then be reacted with an appropriate transition metal compound to form a complex of (I) and the transition metal. For example for early transition metals this may simply be a halide such as TiCl4 or ZrCl4. For late transition metal complexes it may also be a halide such as NiBr2, (COD)NiBr2 (COD is 1,5-cyclooctadiene) or the nickel allyl chloride dimer. In another method of forming the transition metal complex with late transition metals the conjugate acid of (I) can be used to protonate a dialkyl transition metal complex such as (TMEDA)Ni(CH3)2 (TMEDA is N,N,Nxe2x80x2,Nxe2x80x2-tetramethylethylenediamine) to form the desired complex. As noted above, if the transition metal compound is not at this point an active polymerization catalyst by itself, appropriate cocatalysts may be added.
When Z is N, the organometallic compound may be made by the following scheme, illustrated for Ni. If n is 1, an analogous starting material may be used. Complexes of other metals can be made by methods generally described in the immediately preceding paragraph. 
If Z is S or PR , and/or Y is O or PR12, analogous starting materials and methods may be used to make the ligand and the transition metal compound.
Preferred monomers herein are hydrocarbon monomers of the formula H2C=CHR4, or polar olefins of the formula H2C=CHR5CO2R6, and combinations thereof. A particularly preferred hydrocarbon monomer is ethylene (R4 is hydrogen). Another preferred hydrocarbon monomer is an alpha-olefin (R4 is alkyl), particularly when R4 is an n-alkyl containing 1 to 14 carbon atoms, and especially when R4 is methyl (propylene). R6 may be a metal or onium cation (such as ammonium), in which case the polar olefin would be a carboxylate salt. Preferred cations include alkali metal cations and ammonium. For the polar olefins, it is preferred that R6 is alkyl, especially alkyl containing 1 to 4 carbon atoms, and/or R5 is a covalent bond or xe2x80x94(CH2)rxe2x80x94 wherein r is 1 to 19. A particularly preferred combination of monomers is ethylene with one or more alpha-olefins, polar olefins and/or a cyclopentene, especially ethylene with one or more polar olefins. In all instances the corresponding copolymers are formed.
When a polar olefin is present as a (co)monomer, it is preferred that the transition metal is a late transition metal, particularly Ni, Pd or Cu, more preferably Ni. Useful polar olefins include those of the general formula H2C=CHR15E, wherein R15 is alkylene, alkylidene or a covalent bond, especially xe2x80x94(CH2)xxe2x80x94 wherein x is 0 or an integer of 1 to 20 and E is a polar group. Useful polar groups E include xe2x80x94CO2R14, xe2x80x94CO2H, xe2x80x94C(O)NR142 and xe2x80x94OR14, and xe2x80x94CO2R14 and xe2x80x94OR14 are more preferred, wherein each R14 is hydrogen, hydrocarbyl or substituted hydrocarbyl, preferably alkyl or substituted alkyl. For any olefin other than a norbornene, cyclopentene and/or a styrene, it is preferred that it be copolymerized with ethylene. An especially preferred olefin is ethylene (alone). Typically CO and polar comonomers will be used with a hydrocarbon olefin such as ethylene to form a copolymer.
When in the polymerization process and in the metal complex Z is O and M is Ni, it is preferred that the olefin(s) to be polymerized comprise at least one polar olefin, except when said complex is further complexed with a Lewis acid (see above). Also when M is Ni in the transition metal complex and Y is NR12, it is preferred that Z is not O.
In the polymerization process herein, the temperature at which the polymerization is carried out is about xe2x88x92100xc2x0 C. to about +200xc2x0 C., preferably about xe2x88x9260xc2x0 C. to about 150xc2x0 C., more preferably about xe2x88x9220xc2x0 C. to about 100xc2x0 C. The pressure of a gaseous olefin such as ethylene at which the polymerization is carried out is not critical, atmospheric pressure to about 275 MPa being a suitable range. Liquid olefins may be present in virtually any concentration although the polymerization may be slowed down by high concentrations of polar olefins.
When a polar comonomer and ethylene are present, and a Ni complex (Zwitterionic or not) is used in the polymerization catalyst system, it is preferred that the polymerization process be run at a temperature of about 50xc2x0 C. or more, more preferably 60xc2x0 C. to about 170xc2x0 C., and an ethylene partial pressure of at least about 700 kPa. More preferably the temperature range is about 80xc2x0 C. to about 140xc2x0 C. and/or a lower ethylene pressure is about 5.0 MPa or more, and/or a preferred upper limit on ethylene pressure is about 200 MPa, especially preferably about 20 MPa. The polymerization process herein may be run in the presence of various liquids, particularly aprotic organic liquids. The catalyst system, olefinic monomer(s), and/or polymer may be soluble or insoluble in these liquids, but obviously these liquids should not prevent the polymerization from occurring. Suitable liquids include alkanes, cycloalkanes, selected halogenated hydrocarbons, and aromatic hydrocarbons. Specific useful solvents include hexane, toluene, benzene, methylene chloride, 1,2,4-trichlorobenzene and p-xylene.
The olefin polymerizations herein may also initially be carried out in the xe2x80x9csolid statexe2x80x9d by, for instance, supporting the transition metal compound on a substrate such as silica or alumina, activating if necessary it with one or more cocatalysts and contacting it with the olefin(s). Alternatively, the support may first be contacted (reacted) with cocatalysts (if needed) such as an alkylaluminum compound, and then contacted with an appropriate transition metal compound. The support may also be able to take the place of a Lewis or Bronsted acid, for instance an acidic clay such as montmorillonite, if needed. These xe2x80x9cheterogeneousxe2x80x9d catalysts may be used to catalyze polymerization in the gas phase or the liquid phase. By gas phase is meant that a gaseous olefin is transported to contact with the catalyst particle. For the copolymerization of polar olefins using supported catalysts, especially in a liquid medium, a preferred case is when the ligand is covalently attached to the support, which helps prevent leaching of the transition metal complex from the support.
In all of the polymerization processes described herein oligomers and polymers of olefins are made. They may range in molecular weight from oligomeric POs (polyolefins), to lower molecular weight oils and waxes, to higher molecular weight POs. One preferred product is a PO with a degree of polymerization (DP) of about 10 or more, preferably about 40 or more. By xe2x80x9cDPxe2x80x9d is meant the average number of repeat units in a PO molecule.
Depending on their properties, the POs made by the processes described herein are useful in many ways. For instance if they are thermoplastics, they may be used as molding resins, for extrusion, films, etc. If they are elastomeric, they may be used as elastomers. If they contain functionalized monomers such as acrylate esters, they are useful for other purposes, see for instance previously incorporated U.S. Pat. No. 5,880,241.
It is believed that the late transition metal (such as Ni) containing catalysts used herein often give polymers which have unusual branching patterns, see for instance previously incorporated U.S. Pat. No. 5,880,241 and Z. Guan, et al., Science, vol. 283 p. 2059-2062 (1999). On the other hand, early transition metal (such as Ti and Zr) containing catalysts usually give polymers with more conventional branching, such as those made by Ziegler-Natta or metallocene polymerization catalysts.
Depending on the process conditions used and the polymerization catalyst system chosen, the POs may have varying properties. Some of the properties that may change are molecular weight and molecular weight distribution, crystallinity, melting point, and glass transition temperature. Except for molecular weight and molecular weight distribution, branching can affect all the other properties mentioned, and branching may be varied (using the same nickel compound) using methods described in previously incorporated U.S. Pat. No. 5,880,241.
It is known that blends of distinct polymers, that vary for instance in the properties listed above, may have advantageous properties compared to xe2x80x9csinglexe2x80x9d polymers. For instance it is known that polymers with broad or bimodal molecular weight distributions may be melt processed (be shaped) more easily than narrower molecular weight distribution polymers. Thermoplastics such as crystalline polymers may often be toughened by blending with elastomeric polymers.
Therefore, methods of producing polymers which inherently produce polymer blends are useful especially if a later separate (and expensive) polymer mixing step can be avoided. However in such polymerizations one should be aware that two different catalysts may interfere with one another, or interact in such a way as to give a single polymer.
In such a process the transition metal containing polymerization catalyst disclosed herein can be termed the first active polymerization catalyst. A second active polymerization catalyst (and optionally one or more others) is used in conjunction with the first active polymerization catalyst. The second active polymerization catalyst may be another late transition metal catalyst, for example as described in previously incorporated U.S. Pat. Nos. 5,880,241, 6,060,569, 6,174,795 and S. D. Ittel, et al., Chem. Rev., vol. 100, p. 1169-1203 (2000) (and references cited therein), as well as U.S. Pat. Nos. 5,714,556 and 5,955,555 which are also incorporated by reference herein as if fully set forth. Other useful types of catalysts may also be used for the second active polymerization catalyst. For instance so-called Ziegler-Natta and/or metallocene-type catalysts may also be used. These types of catalysts are well known in the polyolefin field, see for instance Angew. Chem., Int. Ed. Engl., vol. 34, p. 1143-1170 (1995), EP-A-0416815 and U.S. Pat. No. 5,198,401 for information about metallocene-type catalysts, and J. Boor Jr., Ziegler-Natta Catalysts and Polymerizations, Academic Press, New York, 1979 for information about Ziegler-Natta-type catalysts, all of which are hereby included by reference. Many of the useful polymerization conditions for all of these types of catalysts and the first active polymerization catalysts coincide, so conditions for the polymerizations with first and second active polymerization catalysts are easily accessible. Oftentimes the xe2x80x9cco-catalystxe2x80x9d or xe2x80x9cactivatorxe2x80x9d is needed for metallocene or Ziegler-Natta-type polymerizations. In many instances the same compound, such as an alkylaluminum compound, may be used as an xe2x80x9cactivatorxe2x80x9d for some or all of these various polymerization catalysts.
In one preferred process described herein the first olefin(s) (olefin(s) polymerized by the first active polymerization catalyst) and second olefin(s) (the monomer(s) polymerized by the second active polymerization catalyst) are identical. The second olefin may also be a single olefin or a mixture of olefins to make a copolymer.
In some processes herein the first active polymerization catalyst polymerizes one or more olefins, a monomer that may not be polymerized by said second active ploymerization catalyst, and/or vice versa. In that instance two chemically distinct polymers may be produced. In another scenario two monomers would be present, with one polymerization catalyst producing a copolymer, and the other polymerization. catalyst producing a homopolymer.
Likewise, conditions for such polymerizations, using catalysts of the second active polymerization type, will also be found in the appropriate above mentioned references.
Two chemically different active polymerization catalysts are used in this polymerization process. The first active polymerization catalyst is described in detail above. The second active polymerization catalyst may also meet the limitations of the first active polymerization catalyst, but must be chemically distinct. For instance, it may utilize a different ligand that differs in structure between the first and second active polymerization catalysts. In one preferred process, the ligand type and the metal are the same, but the ligands differ in their substituents.
Included within the definition of two active polymerization catalysts are systems in which a single polymerization catalyst is added together with another ligand, preferably the same type of ligand, which can displace the original ligand coordinated to the metal of the original active polymerization catalyst, to produce in situ two different polymerization catalysts.
The molar ratio of the first active polymerization catalyst to the second active polymerization catalyst used will depend on the ratio of polymer from each catalyst desired, and the relative rate of polymerization of each catalyst under the process conditions. For instance, if one wanted to prepare a xe2x80x9ctoughenedxe2x80x9d thermoplastic polyethylene that contained 80% crystalline polyethylene and 20% rubbery polyethylene, and the rates of polymerization of the two catalysts were equal, then one would use a 4:1 molar ratio of the catalyst that gave crystalline polyethylene to the catalyst that gave rubbery polyethylene. More than two active polymerization catalysts may also be used if the desired product is to contain more than two different types of polymer.
The polymers made by the first active polymerization catalyst and the second active polymerization catalyst may be made in sequence, i.e., a polymerization with one (either first or second) of the catalysts followed by a polymerization with the other catalyst, as by using two polymerization vessels in series. However it is preferred to carry out the polymerization using the first and second active polymerization catalysts in the same vessel(s), i.e., simultaneously. This is possible because in most instances the first and second active polymerization catalysts are compatible with each other, and they produce their distinctive polymers in the other catalyst""s presence. Any of the processes applicable to the individual catalysts may be used in this polymerization process with 2 or more catalysts, i.e., gas phase, liquid phase, continuous, etc.
The polymers produced by this process may vary in molecular weight and/or molecular weight distribution and/or melting point and/or level of crystallinity, and/or glass transition temperature and/or other factors. The polymers produced are useful as molding and extrusion resins and in films as for packaging. They may have advantages such as improved melt processing, toughness and improved low temperature properties.
Catalyst components which include transition metal complexes of (I), with or without other materials such as one or more cocatalysts and/or other polymerization catalysts are also disclosed herein. For example, such a catalyst component could include the Ni complex supported on a support such as alumina, silica, a polymer, magnesium chloride, sodium chloride, etc., with or without other components being present. It may simply be a solution of the complex, or a slurry of the complex in a liquid, with or without a support being present.
Hydrogen or other chain transfer agents such as silanes (for example trimethylsilane or triethylsilane) may be used to lower the molecular weight of polyolefin produced in the polymerization process herein. It is preferred that the amount of hydrogen present be about 0.01 to about 50 mole percent of the olefin present, preferably about 1 to about 20 mole percent. The relative concentrations of a gaseous olefin such as ethylene and hydrogen may be regulated by varying their relative partial pressures.
In the Examples except where noted, all pressures are gauge pressures. In the Examples the following abbreviations are used:
xcex94Hfxe2x80x94heat of fusion in J/g
Amxe2x80x94amyl
Arxe2x80x94aryl
BAFxe2x80x94B(3,5-C6H3xe2x80x94(CF3)2)4xe2x88x92
BArFxe2x80x94B(C6F5)4xe2x88x92
BHTxe2x80x942,6-di-t-butyl-4-methylphenol
BQxe2x80x941,4-benzoquinone
Buxe2x80x94butyl
Bu2Oxe2x80x94dibutyl ether
CBxe2x80x94chlorobenzene
Cmpdxe2x80x94compound
Cyxe2x80x94cyclohexyl
DMSOxe2x80x94dimethylsulfoxide
DSCxe2x80x94differential scanning calorimetry
Exe2x80x94ethylene
E-10-Uxe2x80x94ethyl 10-undecylenate
EGxe2x80x94end-group, refers to the ester group of the acrylate being located in an unsaturated end group of the ethylene copolymer
EGPEAxe2x80x942-phenoxyethyl acrylate
Eocxe2x80x94end-of-chain
Equivxe2x80x94equivalent
Etxe2x80x94ethyl
Et2Oxe2x80x94diethyl ether
GPCxe2x80x94gel permeation chromatography
HAxe2x80x94hexyl acrylate
Hexxe2x80x94hexyl
ICxe2x80x94in-chain, refers to the ester group of the acrylate being bound to the main-chain of the ethylene copolymer
Incorpxe2x80x94incorporation
i-Prxe2x80x94i-propyl
LAxe2x80x94Lewis acid
M.W.xe2x80x94molecular weight
MAxe2x80x94methyl acrylate
Mexe2x80x94methyl
MeOHxe2x80x94methanol
MIxe2x80x94melt index
Mnxe2x80x94number average molecular weight
Mpxe2x80x94peak average molecular weight
Mwxe2x80x94weight average molecular weight
Ndxe2x80x94not determined
PDIxe2x80x94polydispersity; Mw/Mn
PExe2x80x94polyethylene
Phxe2x80x94phenyl
PMAOxe2x80x94polymethylaluminoxane
Pressxe2x80x94pressure
RBxe2x80x94round-bottomed
RIxe2x80x94refractive index
RT or Rtxe2x80x94room temperature
t-Buxe2x80x94t-butyl
TCBxe2x80x941,2,4-trichlorobenzene
Tempxe2x80x94temperature
THFxe2x80x94tetrahydrofuran
TOxe2x80x94Number of turnovers per metal center=(moles monomer consumed, as determined by the weight of the isolated polymer or oligomers) divided by (moles catalyst)
TONxe2x80x94turnovers, moles of monomer (olefin) polymerized per mole of transition metal present
Total Mexe2x80x94total number of methyl groups per 1000 methylene groups as determined by 1H or 13C NMR analysis
UVxe2x80x94ultraviolet
All operations related to the ligand/catalyst syntheses were performed in a nitrogen drybox or using a Schlenk line with nitrogen protection. Anhydrous solvents were used. Solvents were distilled from drying agents under nitrogen using standard procedures, for instance THF from sodium benzophenone ketyl. Ni[II] allyl chloride was prepared according to the literature (Angew. Chem. Int. Ed. Engl., vol. 5, p. 151-266 (1966)). NMR spectra were recorded using a Bruker 500 MHz spectrometer.
The following transition metal compounds were made: 